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photoperiodism

[ foh-tuh-peer-ee-uh-diz-uhm ]
/ 藢fo蕣 t蓹藞p瑟蓹r i 蓹藢d瑟z 蓹m /
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noun Biology.
the response, as affecting growth or reproduction, of an organism to the length of exposure to light in a 24-hour period.
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Also called pho路to路pe路ri路o路dic路i路ty [foh-toh-peer-ee-uh-dis-i-tee]. /藢fo蕣 to蕣藢p瑟蓹r i 蓹藞d瑟s 瑟 ti/.

Origin of photoperiodism

First recorded in 1915鈥20; photoperiod + -ism
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, 漏 Random House, Inc. 2022

British Dictionary definitions for photoperiodism

photoperiodism
/ (藢f蓹蕣t蓹蕣藞p瑟蓹r瑟蓹藢d瑟z蓹m) /

noun
the response of plants and animals by behaviour, growth, etc, to photoperiods
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition 漏 William Collins Sons & Co. Ltd. 1979, 1986 漏 HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for photoperiodism

photoperiodism
[ f艒鈥瞭艒-p卯r膿-蓹-d沫z鈥采檓 ]

The response of an organism to changes in its photoperiod, especially as indicated by vital processes. For example, many plants exhibit photoperiodism by flowering only after being exposed to a set amount of daylight, as by requiring either a long or short day to flower. Plant growth, seed germination, and fruiting are also affected by day length. Photoperiodic responses in plants are regulated by special pigments known as phytochromes. In animals, migration, mating, amount of sleep, and other behaviors are also photoperiodic. In many animals, photoperiodism is regulated by the hormone melatonin.
The American Heritage庐 Science Dictionary Copyright 漏 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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